In retail of consumer products there can be some of the following problems theft, misplacement and loss of objects. Each retail object can be outfitted with a radio transmitter that can be used for monitoring each individual object. Individual monitoring of each object can open for the possibility of inventory monitoring, triggering of alerts, and localization of individual objects, as well as for possible mislaid.
It is known how to monitor retail objects using Electronic Article Surveillance (EAS) tags. Typically, an EAS tag is attached to the retail object that should be monitored. In various implementations of EAS systems there can be different types of tags. Examples of tags are active and passive tags. An example of a passive tag is a RFID (Radio-Frequency Identification) tag. Such a tag will return a radio signal when placed in an appropriate RF field, and the RFID tag will then be able to receive and transmit data between over RF. A passive EAS tag will need to receive from an external source the power to transmit, e.g. by electromagnetically induced power. An example of an active EAS tag is a tag that is battery powered and may transmit data over a RF channel.
In prior art anti-theft systems the EAS tags can be active tags. The system includes a central radio device that broadcast a RF signal. As long as an active EAS tag detects the broadcasted signal from the central radio device, this means that everything is in order. In the case of loss of the broadcast signal from the central radio device, the EAS tag will emit an alarm signal.
In a second type of prior art anti-theft systems for retail stores using passive EAS tags, a RFID tag can be attached to a retail object. A store with such a system will have one or more gateway RFID scanners at each customer exit. The RFID tag will be deactivated by the cashier with a RFID deactivator at a purchase. The system will detect when a RFID tags passes through the gateway RFID scanners. If an active RFID tag is detected at the gateway this indicates a retail object exiting the store unpaid.
A common scenario when stealing a retail object is to put the retail object in a sound insulated and RF shielded bag. When the retail object is inserted in to such a bag, the EAS tag alarm will not be audible or will not be detected by a RF scanner at the exit of the store.
In prior art retail object monitoring systems each retail object can be equipped with some type of active or passive tag. In passive tag systems each object or group of objects has to be scanned with a RF scanner to count the number of items. In an active monitoring system each tag can transmit information regarding its presence when needed or requested from a beacon transceiver.
A description from prior art is given in US2014/0210624. It is there proposed a device for monitoring the handling of an object. The device comprises a light sensor, a radio receiver, an analyzing means, a movement sensor and a signaling means where the light sensor trigger activation of the device. The device has the draw back that false alarms is triggered by sudden changes in light conditions like when someone turns the lights on in a store.
Some of the problems with current implementations of retail object monitoring systems are the requirements for bidirectional communication between tags and the system gateway. Having bidirectional RF communication capabilities increase the tag cost and the complexity of the system. The additional RF communication requirements also increase the electrical power needed to operate the tags.
It is a known problem in the field of EAS systems how to handle 1000s of EAS tags within the same system. The problem is to reliably be able to monitor 1000s of EAS tags within the same system and at the same time be alerted in the case of theft.
Thus, the present invention aims at solving at least some of the above mentioned problems. In particular, the present invention has the aim to solve the problem with reliably being able to monitor 1000s of tags within the same system.